The present invention relates to an apparatus for detecting defects in wood, particularly wood which has been processed with a planer.
It is known presently to visually inspect pieces of wood after they have been processed with a planer, in order to categorise them. This process is labour-intensive and time consuming, and requires considerable experience in order to properly grade the wood. Defects such as wane, twist, crook, skip and bow are evaluated.
Canadian patent application no. 2,237,640 describes an apparatus and method for detecting surface defects. The apparatus includes surface shape detection means for obtaining profile trace data of at least one surface of the article at a cross-section, the profile trace data being referenced to a reference system, data processing means for deriving a base reference curve from generally rectangular portions of the profile trace data and defect detecting means comparing the trace data with the base reference curve to recognise a defect induced departure of the trace data with respect to the base reference curve and to produce a defect output signal.
However, the apparatus described in this application does not necessarily work as expected since there are no means provided to maintain the article in a given position while the article is being scanned. Accordingly, the error margin is considerable, and it is extremely difficult for the apparatus to provide accurate results.
It is an object of the invention to provide an apparatus for detecting defects which reduces the computational power required to properly analyse an article by maintaining the article in a predetermined position while it is being scanned.
In accordance with the invention, this object is achieved with an apparatus for detecting defects in wood comprising:
a frame comprising
an inlet for loading and conveying the piece of wood in the apparatus in the scanning direction,
an outlet for releasing the piece of wood from the apparatus;
scanning means located between the inlet and the outlet for scanning said piece of wood, the scanning means including an output for scanned data;
computer means operatively connected to the scanning means for receiving the scanned data and processing said data; and
control means for controlling the inlet and the scanning means and insuring proper synchronization.
The inlet and outlet of the apparatus according to the present invention each comprise at least one roller assembly. Each roller assembly is designed to hold two opposite surfaces of the piece of wood so that the piece of wood is conveyed between said roller assembly. The apparatus is characterized in that each roller assembly are positioned so that when the piece of wood passes by said scanning means, it is held and guided by at least two points.
Another object of the present invention is concerned with a method for detecting defects in wood by using the apparatus of the present invention.